Two Sum IV - Input is a BST

Description

Given a Binary Search Tree and a target number, return true if there exist two elements in the BST such that their sum is equal to the given target.

Example 1:

Input: 
    5
   / \
  3   6
 / \   \
2   4   7
Target = 9
Output: True

 

Example 2:

Input: 
    5
   / \
  3   6
 / \   \
2   4   7
Target = 28
Output: False

 

Solution(javascript)

const findTarget = function (root, k) {
  const map = {}
  let valid = false
  const aux = (node) => {
    if (node) {
      if (map[k - node.val]) {
        valid = true
        return
      }
      map[node.val] = true
      aux(node.left)
      aux(node.right)
    }
  }
  aux(root)
  return valid
}